- Your Ad Here Dutchess County is a county located in the U.S. state of New York. In 2016, the United States Census Bureau gives an population estimate of 294,473. The county seat is Poughkeepsie. Sponsored Links History In 1683, the Province of New York established its first twelve counties, with Dutchess County being one of them. The county was named for Mary of Modena, Duchess of York, second wife of James, Duke of York (later James II, King of England). |